360 Thermostat change.....Lessions learned.

My new-to-me (year model 2000) 360 Modena seemed to be running cooler than I would expect. I figured the thermostat might be stuck open, which wouldn’t be a surprise given the age of the car; however, the symptoms weren’t exactly what a fully open thermostat might produce. After some close observation and test runs I decided to change it, or at least have a close look at what was going on.

The procedure sounds pretty straightforward and I confirmed a few short cuts, but there were a few surprises. First, no need to remove the seats. Sliding the seats forward is sufficient and I didn’t even disconnect the seatbelts. Unfortunately, I discovered that the position of the thermostat housing is above the top edge of the engine access panel. That means that you are working blind for part of the time and getting two hands in there isn’t easy or pain free. The two front bolts aren’t any problem but one of the rear bolts was quite difficult to remove and the other one damned near impossible. I fiddled around with a standard 5mm “Alan wrench”, a “T handle style” hex key wrench, and a 5mm hex key driver on a 1/8” drive ratchet wrench. When I say “hex key driver” I mean the hex key equivalent of a socket; i.e. the thing that attaches to a ratchet wrench.

None of this is made any easier, for me at least, since I’m old, I’m fat, and I’ve got a little bit of arthritis. Dropping a tool, which will go who-knows-where, is almost guaranteed. So I got a length of waxed sail maker’s twine and tied a lanyard onto my tools. That little trick saved me from a LOT of frustration, which was at a high level already. After fiddling around with the aft left bolt for a LONG time, I finally managed to first fit the 5mm hex key driver onto the bolt and then engage it with the 1/8 drive ratchet wrench. I would say if you don’t have these two tools, you shouldn’t even think about doing this job. There is not a lot of clearance behind or beside or above the thermostat housing, so be prepared for a fiddly job.

There is a very thin O ring on the upper part of the thermostat. I would strongly suggest having a new one on hand because the old one may be easily damaged when you remove the thermostat from the housing. The lower seal is much more robust and I was able to reuse mine.

Once I got the old thermostat in hand, the problem was obvious. It was stamped 70C. No wonder my car ran too cool. Testing it, alongside the new 80C thermostat revealed that they responded at the proper temperature and both opened fully, but the old one wouldn’t quite close all the way. Mystery solved.

Why someone would install a 70C thermostat is beyond my comprehension. It doesn’t help the car run cooler under conditions of hot weather or hard driving. All it does is make it run too cool, which is silly and potentially damaging to the engine.
Putting everything back together was a more satisfying job and went quickly. I used a bit of masking tape to fasten the bolts and washers to the hex driver so that I could insert the bolts into the mounting holes without dropping anything.

Now the car warms up rapidly to 80C and stabilizes there. Plus I have a fresh load of the proper coolant. Call me cynical, but I’m not totally convinced that the past service history actually involved replacing the coolant. It’s just too easy for some mechanic to say, “Well, they claim that it a Lifetime Coolant so as long as it’s not too rusty or oily, no need to change it. The owner will never know the difference.”

 

I got mine from Superperformance.co.uk for 74 British Pounds.

I didn't open the drains on the engine block, so I can't claim to have drained the entire system. But it did park on a slope (nose down) and drained the system via the radiator drains. Then I refilled with water, ran the engine with the heater on until the thermostat opened, and drained again. I did this about 5 or six times until I couldn't detect any coolant in the system. Then I let it drain while I removed the thermostat.

When I refilled, I added 9L of coolant and topped off with distilled water. I'm sure there was some tap water trapped in the system, but my tap water doesn't have a real high mineral content. Assuming what was left in the system was nearly pure tap water, I believe I have a 50% coolant mixture (in my 18L system) and a mix of tap and distilled water.

I had to order the Arexons ROLIN ALUX VIOLA coolant. It's supposed to work well with tap water (even hard tap water), so I'm going on the assumption that a little trapped low mineral tap water won't do much harm and I figure my multi-flush routine is better than mixing the new coolant with trapped old coolant (Shell) diluted with unknown water.

 

I couldn't find any cross reference after looking for a good long time. Wouldn't you know it, just after I bought my genuine Ferrari part someone mentioned that a BEHR 208279 (or BEHR 2.082.79) thermostat will fit.

WARNING: I have no idea if this is true or not.

 

I"m interested even though I will be a while before I do it again. Can you publish it here?

 

Not quite. The numbers for my old thermostat (a Wahler, made in Germany), working from top to bottom on your drawing, are: 66.4mm, 55.1mm, 25.1mm, and 43.0mm.

It's too late to measure my new one, unfortunately.

The least significant number is the height 58mm, assuming the top isn't too tall to fit inside the housing and I don't think it is. I think the one in the drawing would be fine IF the width of the part just above the upper 67mm flange is 60mm. That is a tight fit in the housing and is sealed with the very thin O ring. If the maximum overall diameter of 67mm is too great, that thin edge could be reduced without too much trouble, but the step just above that measurement point is important because anything larger than 60mm won't fit and anything much smaller than 60mm will leak, at least in my housing.

My thermostat housing looked like a mass produced part, but it might have been hand hammered out of one of Mamma's old cooking pots. Who knows with Ferrari?

What is the source of your drawing?

 

Racing has nothing to do with it. Running a car too cool is NOT good for engine longevity.

Your water temp should RAPIDLY go up to very near the unmarked 1/4 point (around 80C). By rapidly I mean within 5 minutes or so after clearing your driveway; ten minutes max if it's very cold outside.

And it should stay there all the time no matter the outside temperature unless it's VERY hot, or you flog the car really hard, or unless you get stopped in traffic. Then it should go up to around 93C or so when the fans cut in. In severe conditions it might go a bit higher, but if the fans and radiators are in good shape, it shouldn't go as high as 100C. but as soon as you re-establish airflow over the radiators by getting back on the highway, it should immediately return to around 80C.

If your car is slow to warm up, it's a good bet that you need to change the thermostat either because it's the wrong type or because it isn't functioning properly.